This study aims to evaluate the clinical effectiveness of contemporary resin-based adhesive systems by retention rate of resin restorations placed in non carious cervical lesions with four different adhesive strategies: 3 and 2 steps etch-and-rinse adhesive system, 2 and 1 step self-etch adhesive systems.

The etch-and-rinse (3 and 2 steps) and self-etch (1 and 2 steps) adhesive systems allow the bond between the resins restorations with the dental substrates, but they have mechanism of action different.

The success of resin composite restorations is reliant upon adhesion to the underlying tooth via adhesive systems. The mechanism of adhesion to enamel and dentine could be involved for one hand, the etching the substrates with 30-40% phosphoric acid, followed by the application of a primer and subsequently an adhesive resin 3 steps etch-and- rinse approach or 2 steps when to combine the primer and adhesive into one bottle. For another hand, the self- etch systems with acid monomers in their primer, allow conditioning the surface without phosphoric acid step. So, they consist of either a self-etching primer accompanied by an adhesive resin applied as a subsequent step (2 steps) or a self-etch adhesive, which does not require a separate primer (1 step).

Inclusion Criteria:

• Good general health,
• Patients with acceptable oral hygiene level,
• Patients with at least 20 teeth under occlusion.
• Patients with at least four non-carious cervical lesions in four different teeth
• Patients with maximum of eight lesions that needed to be restored.
• These lesions had to be non-carious, non-retentive, deeper than 1 mm, and involve both the enamel and dentin of vital teeth without mobility.

Exclusion Criteria:

• Patients with extremely poor oral hygiene,
• Patients with severe or chronic periodontitis,
• Patients with heavy bruxism habits.